Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/0002—Controlling intake air
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
  • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
  • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
  • F01N3/22—Control of additional air supply only, e.g. using by-passes or variable air pump drives
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
  • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
  • F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
  • F01N3/025—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using fuel burner or by adding fuel to exhaust
  • F01N3/0253—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using fuel burner or by adding fuel to exhaust adding fuel to exhaust gases
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
  • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
  • F01N3/105—General auxiliary catalysts, e.g. upstream or downstream of the main catalyst
  • F01N3/106—Auxiliary oxidation catalysts
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
  • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
  • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
  • F01N3/30—Arrangements for supply of additional air
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N9/00—Electrical control of exhaust gas treating apparatus
  • F01N9/002—Electrical control of exhaust gas treating apparatus of filter regeneration, e.g. detection of clogging
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/021—Introducing corrections for particular conditions exterior to the engine
  • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/021—Introducing corrections for particular conditions exterior to the engine
  • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
  • F02D41/024—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus
  • F02D41/025—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus by changing the composition of the exhaust gas, e.g. for exothermic reaction on exhaust gas treating apparatus
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/18—Circuit arrangements for generating control signals by measuring intake air flow
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
  • F02D41/2406—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
  • F02D41/2425—Particular ways of programming the data
  • F02D41/2429—Methods of calibrating or learning
  • F02D41/2451—Methods of calibrating or learning characterised by what is learned or calibrated
  • F02D41/2474—Characteristics of sensors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/30—Controlling fuel injection
  • F02D41/38—Controlling fuel injection of the high pressure type
  • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
  • F02D41/402—Multiple injections
  • F02D41/405—Multiple injections with post injections
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
  • F01N2560/06—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being a temperature sensor
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2610/00—Adding substances to exhaust gases
  • F01N2610/03—Adding substances to exhaust gases the substance being hydrocarbons, e.g. engine fuel
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
  • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
  • F02D41/1446—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being exhaust temperatures
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/12—Improving ICE efficiencies
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/40—Engine management systems

Definitions

• the present invention relates to a method for adaptation of a mass flow sensor which is intended to measure the mass flow of air in an air intake to a combustion engine.
• the invention relates also to a computer programme product comprising computer programme code for implementing a method according to the invention, and to an electronic control unit.
• Compensating for this drift entails regular corrections of the output signals from the mass flow sensor so that the measured values from it concerning the mass flow of air in the air intake are caused to correspond better to the actual mass flow.
• such correction is called "adaptation".
• the adaptation of the mass flow sensor may be done by comparing a measured value of the mass flow of air in the engine's air intake, determined by the mass flow sensor, with a corresponding calculation value determined on the basis inter alia of the engine's speed and volumetric efficiency, and by adapting the mass flow sensor according to the match between the measured value and the calculation value.
• the volumetric efficiency depends on the operating situation, and values for this efficiency are predetermined by the engine manufacturer for various operating situations.
• a problem with this known adaptation method is that the values of the volumetric efficiency are subject to errors which result in impaired adaptation of the mass flow sensor. If the engine is provided with a so-called EGR (exhaust gas recirculation) system for feeding back part of its exhaust gases to its air intake, this feedback has temporarily to be interrupted if the aforesaid calculation value is to be correct. Applying this known adaptation method therefore entails the EGR valve being kept closed during the adaptation process. However, lack of tightness in the EGR valve results in risk that a small amount of exhaust gases may bypass the closed EGR valve during the adaptation process and enter the engine together with the air flowing through the air intake, thereby leading to an incorrect calculation value and consequently poor accuracy in the adaptation of the mass flow sensor.
• EGR exhaust gas recirculation
• the object of the present invention is to propose a novel and advantageous way of adapting a mass flow sensor which is intended to measure the mass flow of air in an air intake to a combustion engine.
• said object is achieved by means of a method having the features defined in claim 1 .
• the method according to the invention comprises the following steps:
• a calculation value which represents the prevailing mass flow of air in the engine's air intake is determined on the basis of said temperature increase value, a first fuel mass flow value representing the mass flow of said injected fuel which, having undergone no combustion, accompanies the exhaust gases, and a second fuel mass flow value representing the mass flow of fuel injected into and burnt in the engine,
• the mass flow sensor is adapted on the basis of the result of that comparison.
• the adaptation method according to the present invention is thus based on comparing a measured value of the mass flow of air in the engine's air intake determined by the mass flow sensor, with a corresponding calculation value, and on the mass flow sensor being adapted according to the match between the measured value and the calculation value.
• a further advantage of the adaptation method according to the invention is that it allows exhaust gas feedback to continue during the adaptation process, which means that any lack of tightness in the EGR valve no longer represents a source of error during the adaptation of the mass flow sensor. Continued exhaust feedback also means that the exhaust emissions during the adaptation process are not subject to the adverse effects which would occur if the feedback was interrupted during the adaptation process.
• the unburnt fuel caused to accompany the exhaust gases in the engine is injected in the form of post-injections into one or more of the engine's cylinders, which post-injections take place so late during the respective power strokes that the fuel thus post-injected does not undergo combustion in the cylinder/cylinders.
• the injectors used for injecting fuel into the engine's cylinders are controllable with great accuracy and provide well-defined amounts of fuel injection. By using one or more of these injectors to inject during the adaptation process the fuel which, having undergone no combustion, is to accompany the exhaust gases, it is possible to arrive at a very accurate value of the mass flow of this fuel, thereby helping to improve the accuracy of the aforesaid calculation value.
• the invention relates also to a computer programme product having the features defined in claim 9 and an electronic control unit having the features defined in claim 1 1 .
• Fig. 1 is a schematic diagram of a combustion engine with relating means for exhaust treatment
• Fig. 2 is a schematic diagram of a combustion engine with relating EGR system and means for exhaust treatment
• Fig. 3 is a schematic diagram of an electronic control unit for implementing a method according to the invention.
• Fig. 4 is a flowchart illustrating a method according to embodiment of the invention.
• the invention is described below as applied to a motor vehicle.
• the invention is nevertheless not confined to this application but may be applied in all contexts where a mass flow sensor is intended to measure the air flow in the air intake to a combustion engine and where an oxidation catalyst or some other device for oxidation of fuel is provided in the exhaust line from the engine, as in a ship or a power station.
• Figs. 1 and 2 depict schematically a combustion engine 1 of a motor vehicle 2.
• the exhaust gases leaving the engine 1 move through an exhaust line 3 and emerge into the surroundings via an exhaust outlet.
• a fuel oxidation device 4 and a particle filter 5 are disposed in series with one another, with the particle filter situated downstream of the fuel oxidation device.
• a mass flow sensor 6 is provided in the air intake 7 to the engine to measure the mass flow of the air which flows through the air intake 7 and thence into the engine's cylinders 8.
• Figs. 1 and 2 illustrate schematically an engine 1 with six cylinders, but the engine may comprise any appropriate number of cylinders.
• Each cylinder 8 of the engine is allocated a specific injector 9 by means of which fuel is injected into the cylinder.
• a pump 10 is provided to supply fuel at high pressure to the injectors 9 from a fuel tank 1 1 .
• a so-called common rail (not depicted), in the form of an accumulator for accumulation of high- pressure fuel which is to be supplied to the injectors 9, is provided in a conventional way between the pump 10 and the injectors.
• An electronic control unit 12 a so-called engine control unit, determines the amount of fuel to be injected by the injectors 9 during each power stroke according to the vehicle's prevailing operating conditions, and regulates the opening time for each injector 9, i.e. the duration of the period of time during which the injector is kept open to inject fuel into the respective cylinder for the purposes of an individual power stroke, according to the fuel injection amount determined.
• the fuel injection amount is controlled inter alia according to the prevailing mass flow of air in the air intake 7, and the control unit 12 is connected to the mass flow sensor 6 in order to receive from it measured values concerning this mass flow of air.
• the fuel oxidation device 4 takes the form of an oxidation catalyst.
• the fuel oxidation device 4 might alternatively take the form of a set of two or more oxidation catalysts connected in series and/or in parallel, or one or more fuel-oxidising units of some other type.
• the injection of fuel is effected here by means of an injection device 20 comprising an injection means 21 in the form of an injection nozzle situated in the exhaust line.
• a pump 22 is provided to supply fuel to the injection means 21 from a fuel tank 1 1 of the vehicle.
• the injection means 21 and the engine's cylinders 8 are arranged to be supplied with the same fuel from a common fuel tank 1 1 , but they might alternatively be arranged to be supplied with the same grade of fuel or different grades of fuel from respective fuel tanks.
• the supply of fuel to said injection means 21 is regulated by means of a regulating valve 23 situated between the fuel tank 1 1 and the injection means 21 .
• the regulating valve 23 is controlled by an electronic control unit 12 which in the examples illustrated takes the form of the same control unit as controls the injectors 9.
• This control unit 12 uses the regulating valve 23 to regulate the amount of fuel injected into the exhaust gases.
• a reduction catalyst e.g. of SCR (selective catalytic reduction) type, might be provided to effect catalytic conversion of environmentally harmful constituents of the exhaust gases to environmentally less harmful substances.
• the vehicle 2 is provided with an EGR (exhaust gas recirculation) system 30 for returning part of the engine's exhaust gases from the exhaust line 3 to the air intake 7.
• the EGR system comprises a return line 31 with an inlet 32 situated in the exhaust line 3 upstream of the oxidation catalyst 4 and the injection means 21 , and an outlet 33 situated in the air intake 7 downstream of the mass flow sensor 6.
• One or more EGR coolers 34 are provided in the return line 31 to cool the returned exhaust gases. The amount of exhaust gases returned is regulated by means of an EGR valve 35.
• a first temperature sensor 13 is provided to measure the temperature of the exhaust gases upstream of the oxidation catalyst 4, and a second temperature sensor 14 is provided to measure the temperature of the exhaust gases downstream of the particle filter 5.
• a third temperature sensor 15 is also provided to measure the temperature of the exhaust gases between the oxidation catalyst 4 and the particle filter 5.
• the control unit 12 is connected to said temperature sensors 13, 14, 15 in order to receive from them measured values concerning the prevailing exhaust temperature at the respective measuring points.
• unburnt fuel is caused to accompany the exhaust gases produced by the engine 1 to the oxidation catalyst 4, in order to be oxidised therein and thereby generate an increase in the temperature of the exhaust gases passing through the oxidation catalyst.
• this fuel is injected into the engine 1 in the form of late post-injections into one or more of the engine's cylinders 8 via the injectors 9 of the respective cylinders. These post- injections are effected so late during the respective power strokes that the fuel thus injected undergoes no combustion in the cylinder/cylinders 8 and therefore passes out from the engine 1 and accompanies the exhaust gases to the oxidation catalyst 4.
• this fuel is injected into the exhaust line 3 by means of the aforesaid injection device 20, i.e. via the injection means 21 .
• part of this fuel is injected in the form of late post-injections into the engine 1 , while the remainder of it is injected via the injection means 21 .
• the control unit 12 determines a temperature increase value TBDOC-ADOC which represents the increase in temperature undergone by the exhaust gases during their passage through the oxidation catalyst 4 as a result of the fuel which accompanies them into, and is oxidised in, the oxidation catalyst.
• the control unit 12 is arranged to determine the temperature increase value AT BIXX ._ AIX)C on the basis of measured values from the aforesaid first and third temperature sensors 13, 15.
• the control unit 12 is arranged to determine the temperature increase value AT BIX)C ADOC on the basis of measured values from the aforesaid first and the second temperature sensors 13, 14.
• the control unit 12 is arranged to calculate the temperature T AIX)C of the exhaust gases at the outlet from the oxidation catalyst 4, in a manner well-known to specialists within the field, on the basis of their temperature downstream of the particle filter 5, i.e. on the basis of measured values from said second temperature sensor 14, and thereafter to compare the temperature thus calculated with that measured by the first temperature sensor 13, in order to determine the temperature increase value AT BIXX ._ AIXK . .
• the control unit 12 is arranged to determine a calculation value ⁇ ⁇ which represents the prevailing mass flow of air in the engine's air intake 7.
• the control unit 12 is arranged to compare this calculation value m mrX with a corresponding measured value m air2 , determined by means of the gas flow sensor 6, concerning the prevailing mass flow of air in the engine's air intake 7, and thereafter to adapt the mass flow sensor 6 in a conventional way on the basis of the result of that comparison if it indicates that such adaptation is needed.
• the adaptation is done by adjustment of the signal processing algorithm which converts the sensor signal from the mass flow sensor to a mass flow value so that the current measured value from the mass flow sensor is caused to correspond better to the current calculation value.
• the control unit 12 uses said temperature increase value M BD0C _ AD(K . , a first fuel mass flow value m fuen representing the mass flow of the unburnt injected fuel which accompanies the exhaust gases to the oxidation catalyst 4, and a second fuel mass flow value m fuell representing the mass flow of the fuel injected via the injectors 9 and burnt in the engine's cylinders 8.
• the control unit 12 Since it controls the injection of the fuel which, having undergone no combustion, is to accompany the exhaust gases, and the injection of the fuel which is to be burnt in the engine's cylinders, the control unit 12 has access to the information needed for determining said first and second fuel mass flow values m fuen , ⁇ , ⁇ .
• Comh is the calorific value of the unburnt fuel which accompanies the exhaust gases
• the calorific value h omh depends on which fuel is used and is therefore predetermined.
• the efficiency ⁇ ⁇ ) of the oxidation catalyst 4 with respect to fuel oxidation depends on the age of the oxidation catalyst, the temperature T BDO of the exhaust gases before the oxidation catalyst, the temperature T AIX)C of the exhaust gases immediately after the oxidation catalyst, and the exhaust mass flow. Values of the efficiency ⁇ ⁇ . for different combinations of these variables may be determined beforehand and be stored in a memory in the form of charted values.
• the exhaust mass flow represents the aggregate of the mass flow of air in the air intake 7, the mass flow of the unburnt injected fuel which accompanies the exhaust gases to the oxidation catalyst 4, and the mass flow of the fuel injected via injectors 9 and is burnt in the engine's cylinders 8.
• the fuel mass flows are known to the control unit 12 and an approximate value of the mass flow of air in the air intake 7 is obtained from the mass flow sensor 6.
• the thermal capacity Cp exh of the exhaust gases passing through the oxidation catalyst 4 depends on their composition, which itself depends on the mass flow of air in the air intake 7, the mass flow of the unburnt injected fuel which accompanies the exhaust gases to the oxidation catalyst 4, and the mass flow of the fuel injected via the injectors 9 and burnt in the engine's cylinders 8.
• the fuel mass flows are known to the control unit 12 and a value of the mass flow of air in the air intake 7 is obtained from the mass flow sensor 6.
• the liability to error of the measured value received from the mass flow sensor 6 entails a certain slight error in the efficiency ⁇ ⁇ of the oxidation catalyst and the thermal capacity Cp exh of the exhaust gases.
• This error certainly reduces the accuracy of the calculation value m airX for the mass flow of air in the air intake 7 but the accuracy of the calculation value m mrX arrived at will nevertheless be sufficient for it to be possible for it to effect meaningful adaptation of the mass flow sensor 6 on the basis of this calculation value m airl .
• this calculation value m airX may be determined in an iterative calculation process whereby the calculation value first arrived at by using the measured value from the mass flow sensor 6 to determine the efficiency ⁇ ⁇ .
• the aforesaid thermal capacity Cp exh has a certain temperature dependency and its value is therefore affected by the temperature of the exhaust gases. Since the temperature of the exhaust gases changes during their passage through the oxidation catalyst 4, the value used for the thermal capacity Cp exh in the above formula may with advantage be the mean value, or a mean value weighted in a manner known to specialists, for the thermal capacity of the exhaust gases across the relevant temperature range between T BDOC and T Am .
• the control unit 12 may be arranged to calculate the current efficiency ⁇ ⁇ . , in a manner well-known to specialists within the field, on the basis of the temperature increase undergone by the exhaust gases during their passage through the particle filter 5, i.e. on the basis of the difference between their temperature measured by the second temperature sensor 14 downstream of the particle filter and their temperature measured by the third temperature sensor 15 upstream of the particle filter.
• the heat transfer coefficient xh-Doc depends on the relevant cross-sectional area for the heat transfer from the exhaust gases to the oxidation catalyst 4 and is therefore area-dependent in the examples illustrated here.
• the adaptation of the mass flow sensor 6 as described above may be effected by means of the electronic control unit 12 which serves as the engine control unit for the engine 1 , as illustrated in Figs. 1 and 2. However, the adaptation of the mass flow sensor 6 might alternatively be effected by means of another electronic control unit which communicates with the engine control unit.
• the aforesaid temperature increase value ⁇ ⁇ - ADOC represents the difference between the temperature T ADO of the exhaust gases immediately after whichever of the fuel oxidising units is situated furthest downstream in the exhaust line 3 and the temperature T BIXX . of the exhaust gases before whichever of the fuel-oxidising units is situated furthest upstream in the exhaust line 3.
• the fuel oxidation device comprises two or more fuel-oxidising units connected in parallel, e.g.
• the temperature increase value T BDOC _ ALX)C represents the difference between the temperature T ADOC of the exhaust gases immediately downstream of a point in the exhaust line 3 where the mutually parallel exhaust manifold flows unite and the temperature T BDOC of the exhaust gases before whichever of the fuel-oxidising units is situated furthest upstream in the exhaust line 3.
• Fig. 4 is a flowchart illustrating an embodiment of a method according to the present invention for adaptation of a mass flow sensor 6 which is intended to measure the mass flow of air in an air intake 7 to a combustion engine 1 .
• step S1 fuel is injected into the engine 1 and/or into the exhaust line 3 downstream of the engine so that this fuel undergoes no combustion but is caused to accompany the exhaust gases produced by the engine to the fuel oxidation device 4 situated in the exhaust line 3, in order to be oxidised in the fuel oxidation device and thereby generate an increase in the temperature of the exhaust gases passing through the fuel oxidation device.
• a temperature increase value AT BIXX ._ AIX)C representing the increase in the temperature of the exhaust gases during their passage through the fuel oxidation device 4 is determined on the basis of measured values from a temperature sensor provided to detect the temperature of the exhaust gases upstream of the fuel oxidation device and another temperature sensor provided to detect the temperature of the exhaust gases downstream of the fuel oxidation device.
• a calculation value m air representing the prevailing mass flow of air in the engine's air intake 7 is determined on the basis of the temperature increase value AT BDOC-AIX)C f rom s * e P S2, a first fuel mass flow value m n representing the mass flow of said injected fuel which, having undergone no combustion, accompanies the exhaust gases, and a second fuel mass flow value m fuel2 representing the mass flow of fuel injected into and burnt in the engine 1 .
• step S4 the calculation value m mA from step S3 is compared with a corresponding measured value m air2 determined by means of the mass flow sensor 6, and as a fifth step S5 the mass flow sensor 6 is adapted on the basis of the result of the comparison at step S4.
• Computer programme code for implementing a method according to the invention is with advantage incorporated in a computer programme which can be read into the internal memory of a computer, e.g. the internal memory of an electronic control unit of a motor vehicle.
• a computer programme is with advantage provided via a computer programme product comprising a data storage medium which can be read by an electronic control unit and which has the computer programme stored on it.
• Said data storage medium is for example an optical data storage medium in the form of a CD ROM disc, a DVD disc etc., a magnetic data storage medium in the form of a hard disc, a diskette, a cassette tape etc., or a flash memory or a memory of the ROM, PROM, EPROM or EEPROM type.
• a computer programme comprises computer programme code for causing an electronic control unit: - to initiate injection of fuel into a combustion engine and/or into an exhaust line downstream of the engine in such a way that this fuel, having undergone no combustion, is caused to accompany the exhaust gases produced by the engine to a fuel oxidation device situated in the exhaust line, in order to be oxidised in the fuel oxidation device and thereby generate an increase in the temperature of the exhaust gases passing through the fuel oxidation device,
• Fig. 3 illustrates very schematically an electronic control unit 40 comprising an execution means 41 , e.g. a central processor unit (CPU), for execution of computer software.
• the execution means 41 communicates with a memory 42, e.g. of the RAM type, via a data bus 43.
• the control unit 40 comprises also a data storage medium 44, e.g. in the form of a flash memory or a memory of the ROM, PROM, EPROM or EEPROM type.
• the execution means 41 communicates with the data storage medium 44 via data bus 43.
• a computer programme comprising computer programme code for implementing a method according to the invention, e.g. in accordance with the embodiment illustrated in Fig. 4, is stored on the data storage medium 44.
• the invention is of course in no way confined to the embodiments described above, since many possibilities for modification thereof are likely to be obvious to a specialist in the field without thereby having to deviate from the basic concept of the invention as defined in the attached claims.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Materials Engineering (AREA)
• Analytical Chemistry (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)
• Exhaust Gas After Treatment (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=44675024

Family Applications (1)

Country Status (3)

Citations (3)

Family Cites Families (5)

• 2010
  • 2010-03-23 SE SE1050268A patent/SE534678C2/sv unknown
• 2011
  • 2011-03-18 EP EP11759792.2A patent/EP2550442B1/de not_active Not-in-force
  • 2011-03-18 WO PCT/SE2011/050299 patent/WO2011119090A1/en active Application Filing

Patent Citations (3)

Also Published As

Similar Documents

Legal Events